1. Field of the Invention
The present invention relates to a method of estimating the amount of communications traffic that would be routed via a transceiver installed at a proposed transceiver location within the coverage area of an existing communications network. The invention has particular utility in relation to determining the most suitable location for, and characteristics of, a microcell-providing transceiver prior to its installation in a cellular telephone network.
2. Related Art
The last few years have seen a strong growth in the use of mobile telephones. Initially, each network operator enabled a mobile telephone service by installing a number of transceivers spaced around the region in which the service was to be made available. These transceivers typically had a range of between one kilometre and several tens of kilometres. In order to maximise the number of simultaneous calls that could be handled by the network, each transceiver was arranged to operate at a set of frequencies different from the frequencies used by each of its neighbours.
Further growth in the number of mobile telephone users meant that network operators had to divide the cells surrounding the transceivers into a plurality of sectors. Again, the frequencies allotted to the different sectors were chosen to be different from those used in neighbouring sectors. By decreasing the size of the areas in which a given set of frequencies was used, the network operators were able to further increase the capacity of their network.
Nevertheless, particularly in urban areas, even this increase in capacity has not been sufficient to cope with the rising demand. Hence many network operators are now installing low power radio transceivers which handle calls in progress within 100 or 200 metres of the transceiver. These low power transceivers are most usefully employed in areas where the number of calls made is exceptionally high, e.g. at railway stations or in shopping centres.
In order for a newly installed low power radio transceiver to be as effective as possible, it is important to position it and configure its characteristics so that it handles as many calls as possible. One example of a characteristic that can be controlled is the size and shape of the coverage area served by the transceiver.
Many conventional techniques for choosing the best location for a additional transceiver involve identifying the sectors or cells of the network which are heavily loaded and then intuitively guessing a number of possible locations for a transceiver from topographical maps of the local area. Having identified such candidate locations, traffic measurements can be made at each of the locations and the most suitable one determined.
One method that might be used to determine the number of calls that would be handled by a transceiver placed at one of the candidate locations would be to place, at the candidate location, an apparatus which emulates most of the functions of an operational transceiver but which is unable to have calls handed over to it. Such an apparatus could be set up to communicate to a mobile switching centre the strength of signals from nearby mobile units. By analysing the data received, the number of calls which would have been routed via the transceiver had it been fully operational can be determined. An example of this technique is seen in International Patent Application WO 96/35305.
However, the present inventor has realised that such a method and apparatus is unnecessarily time-consuming, complex and expensive.